FIG. 29 is a schematic plan view showing one example of a rotating apparatus that is currently used in space. In FIG. 29, a rotating device 260, such as a motor, has four supporting members 261, 262, 263, 264 fitted thereto extending radially. Experimental boxes 270, 271, 272, 273 are fitted to respective ends of the supporting members 261 to 264 and experimental objects, such as plants, are contained in the experimental boxes 270 to 273. In the microgravitational state, such rotating apparatus is driven by the rotating device 260 to rotate at a slow speed of about 1 rotation/second and experiments on the objects in the experimental boxes 270 to 273, while rotating, are carried out.
In the mentioned rotating apparatus, the experimental boxes 270 to 273 are fitted to the ends of the supporting members 261 to 264, so that the end portions thereof become large in the shape. Also, while the rotating apparatus itself is symmetrical around the rotating axis, experimental objects of different kinds and different sizes are contained in the experimental boxes 270 to 273, causing weight imbalances between the experimental objects so contained. Hence, by the rotation, vibration occurs in a rotary shaft as well as in the supporting members 261 to 264 and the experimental boxes 270 to 273, thereby moving the experimental objects or giving a bad influences to them. Also, the rotation is often carried out without knowing the exact weight of the entire rotating apparatus including the experimental devices.
In the prior art rotating apparatus used in space, as described above, vibration occurs during the rotation and is transmitted to the arms or containers, like boxes, (hereinafter such containers are referred to as “boxes”) constituting a rotator, and gives them bad influences. Also, the vibration spreads to the surrounding environment via the rotary shaft and influences the surrounding space equipment and apparatus as well as the control thereof. Such vibration can be solved by structural means to the extent that the vibration is a steady-state vibration that can be known beforehand. But if the vibration has changes of arbitrarily occurring vibration modes, countermeasures therefor are difficult and control thereof is also limited. Thus, further countermeasures therefor are desired.
Also, there are mass imbalances of the experimental objects in the boxes and the vibration occurs due to acceleration caused by the rotation of the experimental objects having the mass imbalances. Many of the experimental objects placed in the boxes are plants or animals that grow, with changes in the mass, thereby causing mass imbalances between each of the boxes. On the other hand, in space, measurements of weights of the experimental objects or measurements of weight imbalances are not so easy as they are on the ground and any appropriate means therefor is desired. If, in microgravitational space, masses of the experimental objects or imbalance amounts thereof can be easily measured, control measures for the vibrational forces caused in the rotating apparatus, while rotating, can be taken more securely.